Phosphonated polysaccharides and gels and process for making same

ABSTRACT

Products and processes that are related to phosphonated polysaccharide compositions, including phosphonated polysaccharide gels, having a substituent degree of substitution with a lower limit of 0.02 and an upper limit of 3, and having a weight average molecular weight with an upper limit of 5,000,000 g/mole, as well as to oil field application or fracturing fluid compositions comprising such phosphonated polysaccharide compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/179,103, filed Jun. 10, 2016, which claims the benefit of U.S.Provisional Patent Application No. 62/173,437 filed Jun. 10, 2015,incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to phosphonated polysaccharides and, inparticular, to processes to prepare phosphonated polysaccharides andphosphonated polysaccharide gels, in particular phosphonatedpolysaccharides, including phosphonated guar and phosphonated guar gels.

BACKGROUND OF THE INVENTION

Many times, fluids when used in industrial or commercial applicationsare viscosified with a polysaccharide to impart desired properties. Forexample, these viscosified fluids in oil field applications can assistin suspending particulates, and assist in maintaining pressuredown-hole. There is a need for improved compositions containingphosphonated polysaccharides and related gels. There is also a need forcompositions containing phosphonated polysaccharides, in particular highDS phosphonated polysaccharides, including phosphonated guar, in theagriculture (e.g., seed boosting, germination, adjuvant) markets, homeand personal care markets, industrial markets, paper and pulp processmarkets, mining markets, among other, that are environmentally friendlyor provide a sustainability benefit.

SUMMARY OF INVENTION

In one aspect, described herein are phosphonated polysaccharides havinga DS of greater than 0.02. In some embodiments, the DS is greater than0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1. In one embodiment, theDS is greater than 0.3, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.8, 0.9,1 or, in other embodiments, 1.2. In some embodiments, the degree ofsubstitution has an upper limit of 3, or an upper limit of 2, or anupper limit of 1.7, or an upper limit of 1.5, or an upper limit of 1.3.In some embodiments, the DS has a lower limit of 0.02, 0.03, 0.04, 0.05,0.06, 0.07, 0.08, 0.09, 0.1, 0.11 or 0.12.

In one aspect, described herein are polysaccharide compositionscomprising at least one phosphonated polysaccharide having a substituentdegree of substitution (DS) with a lower limit of 0.02 and an upperlimit of 3, and having a weight average molecular weight with an upperlimit of 10,000,000 g/mole.

In one embodiment, the substituent degree of substitution (DS) of thepolysaccharide has a lower limit of 0.02, or in another embodiment alower limit of 0.03, or in another embodiment a lower limit of 0.04, orin another embodiment a lower limit of 0.05, or in another embodiment alower limit of 0.06, or in another embodiment a lower limit of 0.07, orin another embodiment a lower limit of 0.08, or in another embodiment alower limit of 0.09, or in another embodiment a lower limit of 0.2, orin another embodiment a lower limit of 0.4, or in another embodiment alower limit of 0.5, or in another embodiment a lower limit of 0.7, or inanother embodiment a lower limit of 0.8, or in another embodiment alower limit of 1, or in another embodiment a lower limit of 1.1, or inanother embodiment a lower limit of 1.2, or in another embodiment alower limit of 1.4, or in another embodiment a lower limit of 1.5.

In one embodiment, the substituent degree of substitution (DS) of thepolysaccharide has an upper limit of 3. In another embodiment, thesubstituent degree of substitution (DS) of the polysaccharide has anupper limit of 2.5. In another embodiment, the substituent degree ofsubstitution (DS) of the polysaccharide has an upper limit of 2.

In one embodiment, the phosphonated polysaccharide is in gel form. Inone embodiment, the phosphonated polysaccharide is a phosphonated guaror a phosphonated guar gel. In one embodiment, the phosphonatedpolysaccharide is a phosphonated hydroxypropyl guar or a phosphonatedhydroxypropyl guar (sometimes referred to herein as “HPG”) gel. In oneembodiment, the phosphonated polysaccharide is a phosphonated guar or aphosphonated hydroxypropyl guar, or gels thereof.

In one embodiment, the phosphonated polysaccharide is selected fromphosphonated guar; phosphonated carboxymethyl guar (CMG); phosphonatedhydroxyethyl guar (HEG); phosphonated hydroxypropyl guar (HPG);phosphonated carboxymethylhydroxypropyl guar (CMHPG); phosphonatedhydrophobically modified guar (HM guar); phosphonated hydrophobicallymodified carboxymethyl guar (HMCM guar); phosphonated hydrophobicallymodified hydroxyethyl guar (HMHE guar); phosphonated hydrophobicallymodified hydroxypropyl guar (HMHP guar); phosphonated hydrophobicallymodified carboxymethylhydroxypropyl guar (HMCMHP guar); or anycombination thereof.

In one embodiment, the polysaccharide composition further comprises oneor more biocides, one or more surfactants, one or more scale inhibitors,one or more stabilizers or any of the foregoing.

In one embodiment, the polysaccharide has a weight average molecularweight with an upper limit of 10,000,000 g/mole. In another embodiment,the polysaccharide has a weight average molecular weight with an upperlimit of 7,000,000 g/mole. In another embodiment, the polysaccharide hasa weight average molecular weight with an upper limit of 5,000,000g/mole. In another embodiment, the polysaccharide has a weight averagemolecular weight with an upper limit of 4,000,000 g/mole.

In another embodiment, the polysaccharide has a weight average molecularweight with an upper limit of 3,700,000 g/mole. In another embodiment,the polysaccharide has a weight average molecular weight with an upperlimit of 3,500,000 g/mole. In another embodiment, the polysaccharide hasa weight average molecular weight with an upper limit of 3,000,000g/mole. In another embodiment, the polysaccharide has a weight averagemolecular weight with an upper limit of 2,500,000 g/mole. In anotherembodiment, the polysaccharide has a weight average molecular weightwith an upper limit of 2,000,000 g/mole.

In another embodiment, the polysaccharide has a weight average molecularweight with an upper limit of 1,000,000 g/mole. In yet anotherembodiment, the polysaccharide has a weight average molecular weightwith an upper limit of 950,000 g/mole. In another embodiment, thepolysaccharide has a weight average molecular weight with an upper limitof 800,000 g/mole. In another embodiment, the polysaccharide has aweight average molecular weight with an upper limit of 750,000 g/mole.In another embodiment, the polysaccharide has a weight average molecularweight with an upper limit of 700,000 g/mole. In a further embodiment,the polysaccharide has a weight average molecular weight with an upperlimit of 600,000 g/mole. In yet another embodiment, the polysaccharidehas a weight average molecular weight with an upper limit of 500,000g/mole.

In one embodiment, the polysaccharide has a weight average molecularweight with a lower limit of 1,000 g/mole. In one embodiment, thepolysaccharide has a weight average molecular weight with a lower limitof 5,000 g/mole. In one embodiment, the polysaccharide has a weightaverage molecular weight with a lower limit of 15,000 g/mole. In anotherembodiment, the polysaccharide has a weight average molecular weightwith a lower limit of 25,000 g/mole. In another embodiment, thepolysaccharide has a weight average molecular weight with a lower limitof 50,000 g/mole. In another embodiment, the polysaccharide has a weightaverage molecular weight with a lower limit of 75,000 g/mole.

In another embodiment, the polysaccharide has a weight average molecularweight with a lower limit of 100,000 g/mole. In yet another embodiment,the polysaccharide has a weight average molecular weight with a lowerlimit of 150,000 g/mole. In another embodiment, the polysaccharide has aweight average molecular weight with a lower limit of 200,000 g/mole. Inanother embodiment, the polysaccharide has a weight average molecularweight with a lower limit of 250,000g/mole. In another embodiment, thepolysaccharide has a weight average molecular weight with a lower limitof 300,000 g/mole. In a further embodiment, the polysaccharide has aweight average molecular weight with a lower limit of 400,000 g/mole. Inyet another embodiment, the polysaccharide has a weight averagemolecular weight with a lower limit of 500,000 g/mole.

In another aspect, described herein are processes to produce aphosphonated polysaccharide comprising the steps of: obtaining anaqueous or semi-aqueous mixture of a polysaccharide; and contacting themixture with an effective amount of haloalkylphosphonic acid tophosphonate the polysaccharide, whereby the resulting phosphonatedpolysaccharide has a substituent degree of substitution with a lowerlimit of 0.02, or in other embodiments, 0.03, or in other embodiments0.05. In one embodiment, the haloalkylphosphonic acid is achloroalkylphosphonic acid. In another embodiment, the halo group (i.e.,halide) is selected from any one of: fluoride, chloride, bromide oriodide. In another embodiment, the substituent group on thealkylphosphonic acid can be any suitable leaving group, e.g., mesylateor tosylate. In one embodiment, the haloalkylphosphonic acid can bereplaced with mesylalkylphosphonic acid or tosylalkylphosphonic acid,wherein the alkyl group is any as described herein.

In one embodiment, the step of contacting the mixture with an effectiveamount of haloalkylphosphonic acid to phosphonate the polysaccharide iscarried out at a temperature of between 60° C. and 90° C., typicallybetween 60° C. and 80° C., more typically between 65° C. and 75° C.

In one embodiment, the step of contacting the mixture with an effectiveamount of haloalkylphosphonic acid, e.g., chloroalkylphosphonic acid, tophosphonated the polysaccharide is carried out under agitation for aperiod of 10 hours or more, typically 12 hours or more, more typically20 hours or more, even more typically 22 hours or more. In anotherembodiment, the process of claim further comprises the step of adding abase to the mixture, typically NaOH. In one embodiment, the pH of themixture is maintained at a pH of least 11. In one embodiment, the pH ofthe mixture is maintained at a pH of least 11.5. In one embodiment, thepH of the mixture is maintained at a pH of least 12. In a furtherembodiment, the pH of the mixture is maintained at a pH of least 12.2.In a further embodiment, the pH of the mixture is maintained at a pH ofleast 12.5. In yet another embodiment, the pH of the mixture ismaintained at a pH of least 13. In a further embodiment, the pH of themixture is maintained at a pH of least 14. In another embodiment, noinitiator is added to the process. Typically, the alkyl group of thehaloalkylphosphonic acid (e.g., chloroalkylphosphonic acid) is from C1to C10. In another embodiment, the alkyl group of thehaloalkylphosphonic acid is from C1 to C5. In a further embodiment, thealkyl group of the haloalkylphosphonic acid is from C1 to C3. In afurther embodiment, the alkyl group of the haloalkylphosphonic acid isfrom C1 to C2. In one embodiment, the haloalkylphosphonic acid ishaloethylphosphonic acid. In another embodiment, the haloalkylphosphonicacid is halomethylphosphonic acid.

In another embodiment, the process further comprises the step oftreating the phosphonated polysaccharide with an effective amount of acrosslinker to produce a crosslinked phosphonated polysaccharide. Inanother embodiment, the phosphonated polysaccharide is in the form of agel.

In another aspect, described herein are methods of treating asubterranean formation, comprising: providing an oilfield applicationfluid comprising the phosphonated polysaccharide having a substituentdegree of substitution with a lower limit of 0.02 or 0.05 as describedherein; and introducing the oilfield application fluid into a wellborepenetrating the subterranean formation.

In one embodiment, the step of introducing the oilfield applicationfluid into the wellbore penetrating the subterranean formation comprisesintroducing the oilfield application fluid at a pressure sufficient tocreate, expand or sustain a fracture in the subterranean formation. Theoilfield application fluid can further comprise one or more surfactants,one or more scale inhibitors, one or more stabilizers or any of theforegoing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a chart of the Viscosity (KcP) of crosslinked andnon-crosslinked polysaccharides at varying rpms.

DETAILED DESCRIPTION OF INVENTION

As used herein, the term “alkyl” means a saturated straight chain,branched chain, or cyclic hydrocarbon radical, including but not limitedto, methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, t-butyl,pentyl, n-hexyl, and cyclohexyl.

As used herein, the term “aryl” means a monovalent unsaturatedhydrocarbon radical containing one or more six-membered carbon rings inwhich the unsaturation may be represented by three conjugated doublebonds, which may be substituted with one or more of carbons of the ringwith hydroxy, alkyl, alkenyl, halo, haloalkyl, or amino, including butnot limited to, phenoxy, phenyl, methylphenyl, dimethylphenyl,trimethylphenyl, chlorophenyl, trichloromethylphenyl, aminophenyl, andtristyrylphenyl.

As used herein, the term “alkylene” means a divalent saturated straightor branched chain hydrocarbon radical, such as for example, methylene,dimethylene, trimethylene.

As used herein, the terminology “(Cr-Cs)” in reference to an organicgroup, wherein r and s are each integers, indicates that the group maycontain from r carbon atoms to s carbon atoms per group.

As used herein, the terminology “surfactant” means a compound that whendissolved in an aqueous medium lowers the surface tension of the aqueousmedium.

As used herein, the term “degree of substitution” as employed herein isthe average substitution of functional groups per anhydro sugar unit inthe polygalactomannan gum. In guar gum, the basic unit of the polymerconsists of two mannose units with a glycosidic linkage and a galactoseunit attached to the C₆ hydroxyl group of one of the mannose units. Onthe average, each of the anhydro sugar units contains three availablehydroxyl sites. A degree of substitution of 3 would mean that all of theavailable hydroxyl sites have been esterified with functional groups.

As used herein, it is understood that “oilfield application fluid” meansany fluid utilized in the processing, extraction or treatment of oil,which in one embodiment includes fluids utilized in and around anoil-producing well. Some oil application fluids include but are notlimited to: well treatment fluids, stimulation fluids, slickwaterfluids, drilling fluids, acidizing fluids, workover fluids, completionfluids, packer fluids, subterranean formation treating fluids,mud-reversal fluids, deposit removal fluids (e.g., asphaltene, wax,oil), wellbore cleaning fluids, cutting fluids, carrier fluids,degreasing fluids, fracturing fluids, spacer fluids, hole abandonmentfluids, among others.

Workover fluids generally are those fluids used during remedial work ina drilled well. Such remedial work includes removing tubing, replacing apump, cleaning out sand or other deposits, logging, etc. Workover alsobroadly includes steps used in preparing an existing well for secondaryor tertiary recovery such as polymer addition, micellar flooding, steaminjection, etc. Fracturing fluids are used in oil recovery operationswhere subterranean is treated to create pathways for the formationfluids to be recovered.

Slickwater fracturing is a type of oil field fracturing application,which utilizes a low viscosity aqueous fluid to induce, enlarge and/orexpand a fracture in a subterranean formation. Generally, slickwaterfluids contain water having sufficient friction reducing agent tominimize the tubular friction pressures downhole, which viscosities areslightly higher than water or brine without the friction reducing agent.

In one embodiment, a new functional polysaccharide has been synthesizedand a new process has been developed to prepare it. The phosphonatedpolysaccharide can be prepared from different molecular weightpolysaccharides. In one embodiment, the phosphonated polysaccharide is aphosphonated guar or phosphonated derivatized guar.

In one embodiment, the degree of substitution of the phosphonated unitswithin the guar chain can be modified from 0.06 up to 0.7. In oneembodiment, phosphonated guars were prepared starting from either nativeguar or hydroxypropyl guar. Due to the panel of samples which can beprepared, the obtained derivatives could be used in differentapplications: fracturing for the Oil and Gas industry, flocculation ofbauxite in mining, complexes with clay to yield structured gel forcosmetic application, physical complex with ionic liquids to yieldionogel like high strength polyelectrolyte gel for gas adsorptionapplication, agrochemistry.

The reaction does not involve the use of an initiator (or initiatoragent) which could be difficult to remove during the purificationprocess. In one embodiment, no initiator is added in the process. Inanother embodiment, no or minimal initiator is added to the reactionmixture. In another embodiment, no or minimal initiator is added duringany steps of the process.

Described herein are phosphonated polysaccharides and methods ofpreparing such phosphonated polysaccharides. Also described herein arephosphonated polysaccharide compositions and methods of preparing suchphosphonated polysaccharide compositions. The polysaccharidecompositions, in one embodiment, contain at least one phosphonatedpolysaccharide and, optionally, at least one additional component.

In one embodiment, oilfield application fluids and oilfield compositionscan be prepared utilizing the phosphonated polysaccharide as describedherein. Described herein are also methods of treating a subterraneanformation, comprising:—providing an oil field application fluid asdescribed herein; and—introducing the oilfield application fluid into awellbore penetrating the subterranean formation.

In one embodiment, the method of treating a subterranean formationcomprises -introducing an oil field composition into a wellborepenetrating the subterranean formation, whereby the oil fieldcomposition comprises a phosphonated polysaccharide, as describedherein. Introducing the oilfield application fluid or oilfieldcomposition into the wellbore is typically performed at a pressuresufficient to create, expand or sustain a fracture in the subterraneanformation.

In one embodiment, the preparation of polysaccharide (which includesderivatives of such polysaccharides), which in one embodiment is a guar,includes reacting the polysaccharide or guar in a semi-dry, dry orpowder form suspension to add with a neutralized haloalkylphosphonicacid (e.g., chloroalkylphosphonic acid) solution reagent in water (or amixture of water and water miscible solvent e.g., alcohol medium). Inone embodiment, no catalyst or initiator is added. In one embodiment,the guar is native guar, HPG or CMHPG. Typically, thehaloalkylphosphonic acid is neutralized in solution with an alkalinebase to adjust the pH to between about 5.5 and 8.5. In some embodiments,the pH of the aqueous solution of haloalkylphosphonic acid and alkalinebase is adjusted to between 6 and 8. In another embodiment, the pH ofthe aqueous solution of haloalkylphosphonic acid and alkaline base isadjusted to between 6.5 and 7.5. In another embodiment, the pH of theaqueous solution of haloalkylphosphonic acid and alkaline base isadjusted to between 6.8 and 7.2.

The temperature of the reaction mixture can be increased to (or ismaintained at) between about 40° C. and about 75° C. In one embodiment,the reaction temperature has a lower limit of 60° C. or 65° C. or 70° C.or 75° C. or 80° C. In one embodiment, the reaction temperature isbetween about 60° C. and about 80° C.

The mixture is stirred or agitated (constantly or at intervals) for aperiod of time sufficient to ensure complete reaction of the reactants,which, in some embodiments is greater than about 10 hours. In anotherembodiment, the mixture is agitated constantly or at time intervals forgreater than about 12 hours. In another embodiment, the mixture isagitated constantly or at time intervals for greater than about 16hours. In another embodiment, the mixture is agitated constantly or attime intervals for greater than about 20 hours. In another embodiment,the mixture is agitated constantly or at time intervals for greater thanabout 22 hours. In another embodiment, the mixture is agitatedconstantly or at time intervals for greater than about 24 hours.

Thereafter, the resulting material can be neutralized to a neutral pH(e.g., pH about 7). Any acid may be selected for use to neutralize thesolution, including strong acids such as hydrochloric acid and sulfuricacid or weak acids such as acetic acid. In one embodiment, acetic acidis used. The amount of acid used is the amount necessary forneutralization.

In another embodiment, the polysaccharide or guar in a semi-dry, dry orpowder form is reacted (with or without a derivatizing agent) in a watermiscible or immiscible solvent e.g., alcohol medium. This is followed bytreatment or with, for example, alkaline base. The alcohol medium is, inone embodiment, aqueous alcohol slurry which provides sufficient waterto provide at least slight swelling of the guar while at the same timemaintain the integrity of the suspended guar particles.

In one embodiment, the polysaccharide powder, typically guar, ischaracterized by a mean particle diameter of 10 microns (pm) to 500microns. In another embodiment, the polysaccharide powder ischaracterized by a mean particle diameter of 10 microns to 100 microns.In yet another embodiment, the polysaccharide powder is characterized bya mean particle diameter of 10 microns to 50 microns. In one embodiment,the polysaccharide powder is characterized by a mean particle diameterhaving a lower limit of 30 microns, in another embodiment, having alower limit of 20 microns, and in another embodiment a preferred lowerlimit of 10 microns. In one embodiment, the polysaccharide powder ischaracterized by a mean particle diameter having an upper limit of 500microns, in another embodiment, having an upper limit of 250 microns,and in another embodiment a preferred upper limit of 100 microns.

The alcohol medium or solvents that are used are, in one embodiment,alcohols including but not limited to monohydric alcohols of 2 to 4carbon atoms such as ethanol, isopropyl alcohol, n-propanol and tertiarybutanol. In one embodiment the alcohol is isopropyl alcohol. Thealkaline base that is used in this process is alkali metal hydroxide orammonium hydroxide, typically, sodium hydroxide. The amount of alkalinebase used can vary from about 10 to about 100% and, typically, fromabout 20 to 50% by weight, based on the weight of polysaccharide, guaror guar derivative utilized.

In some embodiments, a crosslinking agent is used to partially andtemporarily crosslink the guar chains during processing, therebyreducing the amount of water absorbed by the guar during the one or morewashing steps. Borax (sodium tetra borate) is used in one embodiment,where the crosslinking process takes place under alkaline conditions andis reversible allowing the product to hydrate under acidic conditions.The cross-linker used in process can also aid in making the guarparticles harder and therefore less prone to attrition (breaking intosmall particle size particles) while milling. Maintaining the moisturecontent of the derivatized splits at a relatively low level, typically amoisture content of less than or equal to about 90 percent by weight,simplifies handling and milling of the washed derivatized splits. In theabsence of crosslinking, the moisture content of washed derivatizedsplits is relatively high and handling and further processing of thehigh moisture content splits is difficult. In some embodiments, thecrosslinked guar is dispersed in water and the boron crosslinking thenreversed by adjusting the pH of the guar dispersion, to allowdissolution of the guar to form a viscous aqueous solution.

In one embodiment, the phosphonated polysaccharides (through thephosphonate groups) as described herein, are capable of formingcomplexes with metal cations (sometimes herein referred to as“complexing group(s)”). The resulting crosslinked phosphonatedpolysaccharides are capable of forming stable gels having beneficialproperties.

Typically, the complexing groups are groups capable of complexing atleast one chemical species, typically a metal cation, preferably amultivalent metal cation. In one embodiment, the metal cation is forexample selected from Fe3+ and/or Al3+. In one embodiment, the metalcation is selected from any of: copper compounds, magnesium compounds,titanium compounds, vanadium compounds, iron compounds, aluminumcompounds, or mixtures thereof. In some embodiments, the binding energybetween the species (typically the cation) and the complexing group isat least 30 kJ/mol, more preferably at least 35 kJ/mol and morepreferably at least 40 kJ/mol, or even at least 50 kJ/mol, for exampleat least 60 kJ/mol. This binding energy, in some embodiments, does notexceed 200 kJ/mol, and may typically remain less than or equal to 150kJ/mol, typically less than or equal to 120 kJ/mol, for example between50 and 100 kJ mol.

In one embodiment, the polysaccharides include, as a complexing groups,phosphonic acid groups —PO3H (possibly deprotonated in whole or parte.g., phosphonate) and/or phosphoric acid —O—PO 3 H (optionallydeprotonated in whole or part for example in the form of phosphonate),which are groups capable of complexing a large number of metal cations,particularly Fe3+ cations and/or Al3+, among others.

In one embodiment, the phosphonated polysaccharide comprises complexinggroups capable of complexing at least a metal cation, with a bondingenergy between complexing agent and cation of at least 30 KJ/mol. Thecomplexing group comprises in some embodiments, phosphonic acid —PO₃H,optionally deprotonated entirely or partially, and/or phosphoric acid—O—PO₃H, optionally deprotonated in whole or part. The metal cation canbe Fe3+ and/or Al3+, among other listed herein

In some embodiments, the crosslinking agents include but are not limitedto copper compounds, vanadium compounds, zirconium compounds, forexample zirconium (IV), magnesium compounds, glyoxal, titaniumcompounds, for example, titanium (IV), calcium compounds, ironcompounds, aluminum compounds, p-benzoquinone, dicarboxylic acids andtheir salts, compounds and phosphate compounds.

After the reaction, the obtained product is separated by sedimentation,such as but not limited to centrifugation, or filtration (for both splitand powder processes). Prior to such separation, however, intermediatesteps can be taken to purify the product, such as washing. One or morewashing steps can be utilized. In one embodiment, purifying the productin a washing process comprises a first washing step with water orwater/solvent mixture and/or a second washing step with a diluted orundiluted water-solvent mixture (e.g., solvent process).

In one embodiment, the product can be washed with an aqueous medium bycontacting the guar or derivatized guar with the aqueous medium and thenphysically separating the aqueous wash medium, which is in the form ofprocess water or effluent (or guar processing side stream), from theguar or derivatized guar particles. In some embodiments, the processwater can contain residual reactants, traces of the final product,and/or impurities such as by products and un-reacted reagents. Forexample, after the reaction process the swollen splits are dewatered ina filtration system, which is shaken to remove the wash effluent fromthe solids (solid-liquid separation). The filtration system, in oneembodiment, utilizes mesh screening to remove all the process wateralong with particles smaller than the screen mesh opening. Removal ofthe liquids from solid guar particles can be through, for example,centrifugal force, gravity or pressure gradient. Examples include sievefiltering, high flow rate centrifugal screening, centrifugal sifters,decanting centrifuges, and the like. In one embodiment, the mesh screenfrom about 100 mesh (150 microns) to about 500 mesh (25 microns). Inother embodiments, the mesh screen can be up to 700 mesh or greater.

In one embodiment, the polysaccharide is a locust bean gum. Locust beangum or carob bean gum is the refined endosperm of the seed of the carobtree, Ceratonia siliqua. The ratio of galactose to mannose for this typeof gum is about 1:4. In one embodiment, the polysaccharide is a taragum. Tara gum is derived from the refined seed gum of the tara tree. Theratio of galactose to mannose is about 1:3.

In one embodiment, the polysaccharide is a polyfructose. Levan is apolyfructose comprising 5-membered rings linked through β-2,6 bonds,with branching through β-2,1 bonds. Levan exhibits a glass transitiontemperature of 138° C. and is available in particulate form. At amolecular weight of 1-2 million, the diameter of the densely-packedspherulitic particles is about 85 nm.

In one embodiment, the polysaccharide is a xanthan. Xanthans of interestare xanthan gum and xanthan gel. Xanthan gum is a polysaccharide gumproduced by Xathomonas campestris and contains D-glucose, D-mannose,D-glucuronic acid as the main hexose units, also contains pyruvate acid,and is partially acetylated.

In one embodiment, the polysaccharide of the present invention isderivatized or non-derivatized guar. Guar comes from guar gum, themucilage found in the seed of the leguminous plant Cyamopsistetragonolobus. The water soluble fraction (85%) is called “guaran,”which consists of linear chains of (1,4)-β-D mannopyranosyl units-withα-D-galactopyranosyl units attached by (1,6) linkages. The ratio ofD-galactose to D-mannose in guaran is about 1:2.

The guar seeds used to make guar gum are composed of a pair of tough,non-brittle endosperm sections, hereafter referred to as “guar splits,”between which is sandwiched the brittle embryo (germ). After dehulling,the seeds are split, the germ (43-47% of the seed) is removed byscreening. The splits typically contain about 78-82% galactomannanpolysaccharide and minor amounts of some proteinaceous material,inorganic salts, water-insoluble gum, and cell membranes, as well assome residual seedcoat and seed embryo.

In one embodiment, the polysaccharide is selected from guar orderivatized guar.

In one embodiment, the polysaccharide is selected from guar,carboxymethyl guar (CMG), hydroxyethyl guar (HEG), hydroxypropyl guar(HPG), carboxymethylhydroxypropyl guar (CMHPG), cationic guar, cationiccarboxymethyl guar (CMG), cationic hydroxyethyl guar (HEG), cationichydroxypropyl guar (HPG), cationic carboxymethylhydroxypropyl guar(CMHPG), hydrophobically modified guar (HM guar), hydrophobicallymodified carboxymethyl guar (HMCM guar), hydrophobically modifiedhydroxyethyl guar (HMHE guar), hydrophobically modified hydroxypropylguar (HMHP guar), cationic hydrophobically modified hydroxypropyl guar(cationic HMHP guar), hydrophobically modifiedcarboxymethylhydroxypropyl guar (HMCMHP guar), hydrophobically modifiedcationic guar (HM cationic guar) or any combination thereof.

The polysaccharide is, in an alternate embodiment, selected from thegroup comprising: guar (i.e., native guar), carboxymethyl guar (CMG),hydroxyethyl guar (HEG), hydroxypropyl guar (HPG),carboxymethylhydroxypropyl guar (CMHPG), cationic guar, cationiccarboxymethyl guar (CMG), cationic hydroxyethyl guar (HEG), cationichydroxypropyl guar (HPG), or any combination thereof. In yet anothermore preferred embodiment, the polysaccharide is selected fromhydroxypropyl guar (HPG), carboxymethylhydroxypropyl guar (CMHPG),cationic hydroxypropyl guar (cationic HPG), cationiccarboxymethylhydroxypropyl guar (cationic CMHPG) or any combinationthereof.

In an alternative embodiment, the polysaccharide is any one of thefollowing: galactomannan derivatives, glucomannan derivatives, agar,dextran, polyglucose, polyaminoglycan, xanthan polymers, hem icelluloses(xyloglycans, xyloglucans, mannoglycans and mixed-linkage beta-glucans),pectins (d-galacturonan) and lignin. In one embodiment, thepolysaccharide is a cationic polysaccharide, such as, for example,cationic cellulose derivatives, cationic starch derivatives, andcationic guar gum derivatives. In another embodiment, cationicpolysaccharide include salts of hydroxyethyl cellulose reacted withtrimethyl ammonium substituted epoxide (such as Polyquaternium 10),polymeric quaternary ammonium salts of hydroxyethyl cellulose reactedwith lauryl dimethyl ammonium-substituted epoxide (such asPolyquaternium 24), guar hydroxypropyltrimonium chloride, hydroxypropylguar hydroxypropyltrimonium chloride and cationic protein derivatives,such as cocodimonium hydroxypropyl hydrolyzed wheat protein.

In one embodiment the polysaccharide is guar or a derivatized guar. Insome embodiments, the polysaccharide can be selected from any of thefollowing: guar, unwashed guar gum, washed guar gum, cationic guar,carboxymethyl guar (CM guar), hydroxyethyl guar (HE guar), hydroxypropylguar (HP guar), carboxymethylhydroxypropyl guar (CMHP guar), cationicguar, hydrophobically modified guar (HM guar), hydrophobically modifiedcarboxymethyl guar (HMCM guar), hydrophobically modified hydroxyethylguar (HMHE guar), hydrophobically modified hydroxypropyl guar (HMHPguar), cationic hydrophobically modified hydroxypropyl guar (cationicHMHP guar), hydrophobically modified carboxymethylhydroxypropyl guar(HMCMHP guar), hydrophobically modified cationic guar (HM cationicguar), guar hydroxypropyl trimonium chloride, hydroxypropyl guarhydroxypropyl trimonium chloride, starch, corn, wheat, rice, potato,tapioca, waxy maize, sorghum, waxy sarghum, sago, dextrin, chitin,chitosan, alginate compositions, xanthan gum, carageenan gum, cassiagum, tamarind gum, cationic cellulose, cationic polyacrylamide, cationicstarch, gum karaya, gum arabic, pectin, cellulose, hydroxycellulose,hydroxyalkyl cellulose, hydroxyethyl cellulose,carboxymethylhydroxyethyl cellulose, hydroxypropyl cellulose, aderivative of any of the foregoing or a combination of any of theforegoing.

In one embodiment, the starting materials in the process is aderivatized, polysaccharide, typically hydroxypropyl guar orcarboxymethylhydroxypropyl guar. (i.e., these materials can consideredthe starting materials for some embodiments of the process as describedherein).

In one embodiment, the starting nonionically substituted guar gum isthen treated with an alcohol or an alcohol/water solution. In oneembodiment, the alcohol selected may be methanol, ethanol, isopropanol,n-propyl alcohol, n-butyl alcohol and the like. The alcohols may be usedin neat (100%) form or in combination with water, the primaryconsideration being that the alcohol is miscible with water. Treatmentis typically made at elevated temperatures, for example, above 50° C. or60° C., although the temperature can be increased to about 70° C. orgreater.

In one embodiment, mixtures of water and organic solvents are utilized,at between about 10 to about 90 percent water by weight and betweenabout 90 to about 10 percent organic solvent by weight. In anotherembodiment, the use is of between about 80 to about 90% by weightisopropyl alcohol and between about 10 to about 20% by weight water, orin yet another embodiment the solution selected for use is anisopropanol/water mixture, wherein the respective amounts by weight are85% isopropanol and 15% water.

In one embodiment, the amount of alcohol or alcohol water solution to beused in is generally that amount which is necessary to fully saturatethe guar powder. In practice, this amount is usually at least twice theamount by weight of the starting guar powder, and even more preferably,at least three times the amount by weight of the starting guar powder.

The compositions described herein can also contain cationic, anionic,amphoteric or zwitterionic surfactants, as described in greater detailbelow.

The viscoelastic surfactants include zwitterionic surfactants and/oramphoteric surfactants and cationic surfactants. A zwitterionicsurfactant has a permanently positively charged moiety in the moleculeregardless of pH and a negatively charged moiety at alkaline pH. Acationic surfactant has a positively charged moiety regardless of pH. Anamphoteric surfactant has both a positively charged moiety and anegatively charged moiety over a certain pH range (e.g., typicallyslightly acidic), only a negatively charged moiety over a certain pHrange (e.g., typically slightly alkaline) and only a positively chargedmoiety at a different pH range (e.g., typically moderately acidic).

In one embodiment, the cationic surfactant is selected from i) certainquaternary salts and ii) certain amines, iii) amine oxide, iv) andcombinations thereof.

The quaternary salts have the structural formula:

wherein R₁ is a hydrophobic moiety of alkyl, alkylarylalkyl,alkoxyalkyl, alkylaminoalkyl or alkylamidoalkyl. R₁ has from about 18 toabout 30 carbon atoms and may be branched or straight-chained andsaturated or unsaturated. Representative long chain alkyl groups includeoctadecentyl (oleyl), octadecyl (stearyl), docosenoic (erucyl) and thederivatives of tallow, coco, soya and rapeseed oils. The preferred alkyland alkenyl groups are alkyl and alkenyl groups having from about 18 toabout 22 carbon atoms.

R₂, R₃, and R₅ are, independently, an aliphatic group having from 1 toabout 30 carbon atoms or an aromatic group having from 7 to about 15carbon atoms. The aliphatic group typically has from 1 to about 20carbon atoms, more typically from 1 to about 10 carbon atoms, and mosttypically from 1 to about 6 carbon atoms. Representative aliphaticgroups include alkyl, alkenyl, hydroxyalkyl, carboxyalkyl, andhydroxyalkyl-polyoxyalkylene. The aliphatic group can be branched orstraight-chained and saturated or unsaturated. Preferred alkyl chainsare methyl and ethyl. Preferred hydroxyalkyls are hydroxyethyl andhydroxypropyl. Preferred carboxyalkyls are acetate and propionate.Preferred hydroxyalkyl-polyoxyalkylenes are hydroxyethyl-polyoxyethyleneand hydroxypropyl-polyoxypropylene. Examples of aromatic moietiesinclude cyclic groups, aryl groups, and alkylaryl groups. A preferredalkylaryl is benzyl.

X is suitable anion, such as Cl⁻, Br⁻, and (CH₃)₂SO₄ ⁻.

Representative quaternary salts of the above structure includemethylpolyoxyethylene(12-18)octadecanammonium chloride,methylpolyoxyethylene(2-12)cocoalkylammonium chloride, andisotridecyloxypropyl polyoxyethylene (2-12) methyl ammonium chloride.

The amines have the following structural formula:

wherein R₁, R₂, and R₃ are as defined above.

Representative amines of the above structure includepolyoxyethylene(2-15) cocoalkylamines,polyoxyethylene(12-18)tallowalkylamines, andpolyoxyethylene(2-15)oleylamines.

Selected zwitterionic surfactants are represented by the followingstructural formula:

wherein R₁ is as described above. R₂ and R₃ are, independently, analiphatic moiety having from 1 to about 30 carbon atoms or an aromaticmoiety having from 7 to about 15 carbon atoms. The aliphatic moietytypically has from 1 to about 20 carbon atoms, more typically from 1 toabout 10 carbon atoms, and most typically from 1 to about 6 carbonatoms. The aliphatic group can be branched or straight chained andsaturated or unsaturated. Representative aliphatic groups include alkyl,alkenyl, hydroxyalkyl, carboxyalkyl, and hydroxyalkyl-polyoxyalkylene.Preferred alkyl chains are methyl and ethyl. Preferred hydroxyalkyls arehydroxyethyl and hydroxypropyl. Preferred carboxyalkyls are acetate andpropionate. Preferred hydroxyalkyl-polyoxyalkylenes arehydroxyethyl-polyoxyethylene or hydroxypropyl-polyoxypropylene). R₄ is ahydrocarbyl radical (e.g. alkylene) with chain length 1 to 4 carbonatoms. Preferred are methylene or ethylene groups. Examples of aromaticmoieties include cyclic groups, aryl groups, and alkylaryl groups. Apreferred arylalkyl is benzyl.

Specific examples of selected zwitterionic surfactants include thefollowing structures:

wherein R₁ is as described above.

Other representative zwitterionic surfactants include dihydroxyethyltallow glycinate, oleamidopropyl betaine, and erucyl amidopropylbetaine.

Selected amphoteric surfactants useful in the viscoelastic surfactantfluid of the present invention are represented by the followingstructural formula:

wherein R₁, R₂, and R₄ are as described above.

Specific examples of amphoteric surfactants include those of thefollowing structural formulas:

wherein R1 is as described above. X+ is an inorganic cation such as Na+,K+, NH₄+ associated with a carboxylate group or hydrogen atom in anacidic medium.

The oil field compositions described herein, in alternative embodiments,can include (in either the product, process of making of), various otheradditives. Non-limiting examples include stabilizers, thickeners,corrosion inhibitors, mineral oils, enzymes, ion exchangers, chelatingagents, dispersing agents, clay (e.g., Bentonite and attapulgite) andthe like.

EXPERIMENTS

Hydration in Brine Solution

A 15% NaCl/10% CaCl₂.2H20 brine solution was made by adding 300 gm ofsodium chloride and 200 gm of calcium chloride dehydrate to 1500 gm ofwater to make the brine solution called brine 1.

250 ml of brine 1 was taken in a blender jar and 2.4 gm of appropriatephosphonated guar/phosphonated guar derivatives was added to make asolution with concentration of 9.6 gm/liter. The mixing was continuedfor about 15 minutes and then set aside. The viscosity was measuredafter 24 hours using a model OFITE 900 viscometer at 511/sec and 75 F.The samples and the appropriate viscosities are shown in Table 1.

TABLE 1 DS of Sample ID Viscosity, cP phosphonate S1161-124 2.8 0.67Phosphonated guar S1161-140 28.7 0.05 Phosphonated HPG S1161-137 10.90.24 Phosphonated HPG S1161-134 22.4 0.25 Phosphonated guar S1161-1313.2 0.37 Phosphonated guar S1161-127 7.2 0.53 Phosphonated HPG

Crosslinking Test

To 250 ml of deionized water, 5 gm of potassium chloride was added in ablender. While mixing, then 1.8 gm of phosphonated HPG with a DS of 0.05was added to make a solution of 7.2 gm/liter. Mixing was continued andthen set aside. The viscosity was measured after 1 hr to be 29 cP. Then,1.2 gm of sodium thiosulfate was added as high temperature stabilizerand the pH was adjusted using a 25% potassium carbonate solution to 9.5.Then 0.1 ml of Tyzor 217 (a zirconium lactate crosslinker fromDorf-Ketal) crosslinker was added. Then about 45 ml of solution wastransferred to the cup of a Chandler high temperature, high pressureviscometer using R1B5 geometry. The sample had already crosslinkedbefore the Chandler high temperature, high pressure viscometer wasstarted which took approximately 5 minutes. The sample was heated fromroom temperature to 250 F and maintained at 250 F. The viscosity duringthe test @100/sec in shown in the following Table 2.

TABLE 2 Time 5 10 15 30 60 90 120 (min) Start min min min min min minmin Viscosity, 900 1480 467 830 871 732 588 513 cP Temp (F.) 75 80 187240 247 247 247 247

Preparing a 0.5% by weight phosphonated-HPG/Fe(III) gel (150 g)

In an 8 oz wide-mouth glass jar, 99 g of DI water and 0.9 g ofphosphonated-HPG (10% moisture) are introduced at room temperature. Themixture is stirred with an Ultra Turrax homogenizer (Power=1) for 5 min.In a 60 mL plastic jar, FeCl₃6H2O and deionized (DI) water areintroduced, and then stirred at room temperature to dissolve. The ferricion solution is subsequently added to the phosphonated-HPG solution,while under stirring using a magnetic stir bar. The final mixture isleft to sit overnight.

The gel apparent viscosity is evaluated with a Brookfield RV DV-II+®viscometer at room temperature and 20 rpm. A small sample adaptor isused comprising the sample chamber SC4-13R and the spindle SC4-25 orSC4-31 depending on the magnitude of the gel apparent viscosity. 13 g ofgel are inserted into the chamber using spatulas or wide-tip plasticpipette. The viscosity value is read after a 3 minute equilibrationtime.

The viscosity value was read after a 3 minute equilibration time, andthe value was 22.3 KcP.

Procedure for 0.5% wt phosphonated-guar gel/Fe(III) (150 g)

In an 8 oz wide-mouth glass jar, 99 g of DI water and 0.9 g ofphosphonated-guar (10% moisture) are introduced at room temperature. Themixture is stirred with an Ultra Turrax homogenizer (Power=1) for 5 min.In a 60 mL plastic container, FeCl₃.6H2O and deionized (DI) water areintroduced, and then stirred at room temperature to dissolve. The ferricion solution is subsequently added to the phosphonated-guar solution,while under vigorous stirring using a magnetic stir bar. The finalmixture is left to sit overnight.

The gel apparent viscosity is evaluated with a Brookfield RVDV-Il+viscometer at room temperature and 20 rpm. A small sample adaptoris used comprising the sample chamber SC4-13R and the spindle SC4-25 orSC4-31 depending on the magnitude of the gel apparent viscosity. 13 g ofgel are inserted into the chamber using spatulas or wide-tip plasticpipette.

Referring to FIG. 1, the viscosity value is read after a 3 minuteequilibration time, and the value was 19 KcP, as shown in Table 3 below.

Procedure for the preparation of 0.5% wt phosphonated-HPG/Al (III) gel(150 g).

In an 8 oz wide-mouth glass jar, 99 g of DI water and 0.9 g ofphosphonated-HPG (10% moisture) are introduced at room temperature. Themixture is stirred with an Ultra Turrax homogenizer (Power=1) for 5 min.In a 60 mL plastic container, AlCl₃.6H2O and DI water are introduced,and then stirred at room temperature to dissolve. The aluminum ionsolution is subsequently added slowly with a plastic pipette to thephosphonated-guar solution, while under vigorous stirring using amagnetic stir bar.

The final mixture is left to sit overnight. The gel apparent viscosityis evaluated with a Brookfield RV DV-II+® viscometer at room temperatureand 20 rpm. A small sample adaptor is used comprising the sample chamberSC4-13R and the spindle SC4-25 or SC4-31 depending on the magnitude ofthe gel apparent viscosity. 13 g of gel are inserted into the chamberusing spatulas or wide-tip plastic pipette.

Referring to FIG. 1, the viscosity value is read after a 3 minuteequilibration time, and the value was 18.9 KcP, as shown in Table 3below.

Procedure for the preparation of 0.5% CM HPG+Zr crosslinker.

In a blender, 500 mL of DI water were introduced, followed by theaddition of: choline chloride solution and carboxymethyl hydroxypropylguar (CMHPG). The pH is then lowered. The above mixture is mixed in theblender at 1500 rpm for 2 minutes, and then allowed to hydrate bysitting at room temperature. 250 g of the above mixture is removed andits pH is adjusted to 10-10.5, by addition of potassium carbonate.Zirconium crosslinker is then added. The latter mixture is mixed for 15seconds before proceeding to read its viscosity.

The gel apparent viscosity is evaluated with a Brookfield RV DV-II+®viscometer at room temperature and 20 rpm. A small sample adaptor isused comprising the sample chamber SC4-13R and the spindle SC4-25 orSC4-31 depending on the magnitude of the gel apparent viscosity. 13 g ofgel are inserted into the chamber using spatulas or wide-tip plasticpipette. The viscosity value is read after a 3 minute equilibrationtime.

Referring to FIG. 1, the viscosity value was read after a 3 minuteequilibration time, and the value was 18.4 KcP, as shown in Table 3below.

TABLE 3 Sample SC4-31/13R SC4-25/13R 0.5 rpm 20 rpm 0.5% HPG  3.2 KcP 1.2 KcP 0.5% Native guar  3.2 KcP  1.3 KcP 0.5% Xanthan gum 21.7 KcP 1.2 KcP 0.5% Phos-HPG + Al (crosslinker)  114 KcP 18.9 KcP 0.5%Phos-HPG + Fe (crosslinker)  130 KcP 22.3 KcP 0.5% CMHPG + Zr lactate(crosslinker)  105 KcP 18.4 KcP

The gels apparent viscosity are evaluated with a Brookfield RV DV-II+®viscometer at room temperature and 20 rpm. A small sample adaptor isused comprising the sample chamber SC4-13R and the spindle SC4-25 orSC4-31 depending on the magnitude of the gel apparent viscosity. 13 g ofgel are inserted into the chamber using spatulas or wide-tip plasticpipette. The viscosity value is read after a 3 minute equilibrationtime. A 0.5g of polysaccharide, namely hydroxypropyl guar, native guarand xanthan gum are added to 99.5% of DI water upon stirring, andallowed to sit at room temperature overnight, before measuring viscosity

It should be apparent that embodiments and equivalents other than thoseexpressly discussed above come within the spirit and scope of thepresent invention. Thus, the present invention is not limited by theabove description but is defined by the appended claims.

What is claimed is:
 1. A process to produce a phosphonatedpolysaccharide comprising the steps of contacting an effective amount ofhaloalkylphosphonic acid to an aqueous or semi-aqueous mixture of apolysaccharide to phosphonate the polysaccharide, whereby the resultingphosphonated polysaccharide has a substituent degree of substitutionwith a lower limit of 0.05.
 2. The process of claim 1 wherein the lowerlimit of the substituent degree of substitution is 0.055.
 3. The processof claim 1 wherein the lower limit of the substituent degree ofsubstitution is 0.7.
 4. The process of claim 1 wherein the lower limitof the substituent degree of substitution is
 1. 5. The process of claim1 wherein the phosphonated polysaccharide is selected from phosphonatedguar; phosphonated carboxymethyl guar (CMG); phosphonated hydroxyethylguar (HEG); phosphonated hydroxypropyl guar (HPG); phosphonatedcarboxymethylhydroxypropyl guar (CMHPG); phosphonated hydrophobicallymodified guar (HM guar); phosphonated hydrophobically modifiedcarboxymethyl guar (HMCM guar); phosphonated hydrophobically modifiedhydroxyethyl guar (HMHE guar); phosphonated hydrophobically modifiedhydroxypropyl guar (HMHP guar); phosphonated hydrophobically modifiedcarboxymethylhydroxypropyl guar (HMCMHP guar); or any combinationthereof.
 6. The process of claim 1 wherein the at least one phosphonatedpolysaccharide is selected from phosphonated cationic carboxymethyl guar(CMG), phosphonated cationic hydroxyethyl guar (HEG), phosphonatedcationic hydroxypropyl guar (HPG), phosphonated cationiccarboxymethylhydroxypropyl guar (CMHPG), phosphonated cationichydrophobically modified hydroxypropyl guar (cationic HMHP guar),phosphonated hydrophobically modified cationic guar (HM cationic guar)or any combination thereof.
 7. The process of claim 1 wherein the stepof contacting the mixture with an effective amount ofhaloalkylphosphonic acid to phosphonated the polysaccharide is carriedout at a temperature of between 60° C. and 90° C., typically between 60°C. and 80° C., more typically between 65° C. and 75° C.
 8. The processof claim 1 wherein the step of contacting the mixture with an effectiveamount of haloalkylphosphonic acid to phosphonate the polysaccharide iscarried out under agitation for a period of 10 hours or more, typically12 hours or more, more typically 20 hours or more, even more typically22 hours or more.
 9. The process of claim 1 wherein thehaloalkylphosphonic acid is chloroalkylphosphonic acid.
 10. The processof claim 1 further comprising the step of adding a base to the mixture,wherein the base is typically NaOH.
 11. The process of claim 2 whereinthe process further comprises the step of treating the phosphonatedpolysaccharide with an effective amount of a crosslinker to produce acrosslinked phosphonated polysaccharide.
 12. The process of claim 2wherein no initiator is added during the reaction.
 13. A method oftreating a subterranean formation, comprising: providing an oilfieldapplication fluid comprising a polysaccharide composition comprising atleast one phosphonated polysaccharide having a substituent degree ofsubstitution with a lower limit of 0.05 and an upper limit of 3, andhaving a weight average molecular weight with an upper limit of5,000,000 g/mole; and introducing the oilfield application fluid into awellbore penetrating the subterranean formation.
 14. The method of claim13 wherein the step of introducing the oilfield application fluid intothe wellbore penetrating the subterranean formation comprisesintroducing the oilfield application fluid at a pressure sufficient tocreate, expand or sustain a fracture in the subterranean formation. 15.The method of claim 13 wherein the oilfield application fluid furthercomprises one or more surfactants, one or more scale inhibitors, one ormore stabilizers or any combination of the foregoing.
 16. The process ofclaim 1, wherein the phosphonated polysaccharide is further cross-linkedwith a metal cation to form a phosphonated polysaccharide gel.
 17. Theprocess of claim 16, wherein the metal cation is selected from compoundsof aluminum, titanium, iron, vanadium, copper or magnesium.
 18. Theprocess of claim 1, wherein the polysaccharide is a guar or a guarderivative.
 19. The process of claim 1, wherein the metal cation isselected from compounds of aluminum or iron.